They're saying that the tool doesn't fit their priorities for their use case. I suspect you might be trying to say that their use case isn't what the tool is designed for, but you've phrased it in a way that comes across as condescending for not knowing what the tool even does. I'm not sure if you're trying to convince them that the tool would in fact be superior for their use case or if you're unhappy with them for giving this feedback in a context that you think isn't appropriate, but in either case I think it would be more effective to just state your point directly instead of passive-aggressively.